Editing Liver lesions (section)

== '''Non-cirrhotic liver''' ==

* '''Cavernous haemangioma'''
** Commonest hepatic lesion
*** Generally 30-50yo, F:M 3:1
*** Normal AFP
** Benign - blood-filled spaces with slowly-moving blood
*** Subtype: giant haemangioma, which can show up with a central scar
*** Sclerosed - occurs after infarction. Capsular retraction, scarring.
*** Haemangiomatosis - rare - diffuse replacement of liver by haemangiomas
** Features
*** USS
**** Hyperechoic, with no hypoechoic rim
**** No flow on doppler
**** USS contrast agents can be used to clinch the diagnosis
*** CT
**** Noncon: well-demarcated hypodense mass
**** Arterial: discontinuous, nodular peripheral enhancement
**** PV: progressive peripheral enhancement with more centripetal fill-in
**** Delayed: further irregular fill-in, therefore iso or hyper attenuating to liver parenchyma
**** Rim enhancement is NEVER a haemangioma
****
*** Edge often lobulated
*** Progressive infilling
*** MRI is the best test
**** Very high t2 signal
**** Follows blood pool in terms of contrast signal
* '''Focal nodular hyperplasia'''
** Common, especially in young female adults (9:1 F:M, age 35-50)
** Very rarely symptomatic
** Hypoplastic result to vascular insult
** Characteristic fibrous scar in centre of lesion
** Findings
*** Central scar - 40-60% - high T2 signal
**** Beware the central scar!!! Not diagnostic of FNH
*** USS - often subtle
*** CT - 
**** Noncon: hypo or isodense lesion with hypoattenuating centre
**** Arterial: avid uniform arterial enhancement, except for hypoattenuating central scar
**** PV: no washout (it FADES rather than WASHES OUT - that is, still brighter than normal liver on PV), microlobulated border. Usually slightly brighter than background normal liver in PV phase.
**** Delayed: mostly get enhancement of fibrotic scar
***
*** Invisible on pre-contrast, avid uniform arterial enhancement, slightly bright on PV, disappeared on late venous.
* '''Hepatocellular adenoma'''
** True monoclonal neoplasms
*** Can progress to HCC
** Less common than FNH
** Age 20-40
** Usually women (F:M 9:1)
** 80% are single lesions
** A/w:
*** Rupture
*** Growth in response to oestrogen/testosterone
*** Malignant transformation to HCC
*** Glycogen storage diseases
*** Metabolic syndrome
** CT
*** Often look identical to FNH
*** Liver-specific contrast is necessary - these are usually dark in primovist phases
*** Noncon: well-demarcated, hypo or isodense lesion
*** Arterial: peripheral enhancement
*** PV: centripetal flow
*** Delayed: iso or hypodense
***
* '''Liver mets'''
** CT/MRI
*** '''Rim enhancement''' on arterial phase, with early washout
*** PV: progressive enhancement of a thickened rind
*** Delayed: usually hypoattenuating (washout), but occasionally have delayed enhancement due to desmoplastic reaction
*** Dark on primovist phases (don't contain hepatocytes to take up the contrast)
*** Central necrosis common
***
** Hypervascular mets
*** Neuroendocrine most common
*** RCC
*** Melanoma
*** Thyroid
*** Choriocarcinoma
** Screening for liver mets - primovist MRI is best
* '''Intrahepatic cholangiocarcinoma'''
** RFs:
*** Cirrhosis
*** HBV
*** HCV
** CT
*** Noncon: homogenous hypoattenuating mass
*** Arterial: Rim type arterial phase hyperenhancement around a hypodense lesion
*** PV: progressive enhancement with centripetal filling
*** Delayed: iso or hypodense due to abundant fibrosis stroma
*** Capsular reaction
*** Satellite nodules
*** Delayed, cloud-like infilling of central stroma
***
* Hepatic angiomyolipoma
** Seen in a/w tuberous sclerosis, or sporadically
* Fibrolamellar HCC
** Very rare, usually adolescents or young adults, without cirrhosis
** Large well-defined mass with large scar
** Arterial enhancement with washout
** Calcification common
**
* Epithelioid haemangioendothelioma
** Multi-focal lesions
** Geographical 
** Capsular retration
* Hydatid cyst
**
** Parasitic infection with tapeworm
** Hypodense lesion with hyperattenuating wall
** Detachment of laminated membrane from pericyst can be visualised as linear areas of hyperattenuation
** Daughter cysts are located peripherally within the mother cyst; they are usually at a lower density than the mother cyst
* Polycystic liver disease
**
* Biliary cystadenoma and cystadenocarcinoma
**
* Simple hepatic cysts
** Homogenous hypoattenuation (0-10HU)
** Imperceptible wall
** No internal structures
** No enhancement after IV contrast
**